Method and apparatus for cross retransmission between gul and sul

ABSTRACT

Provided herein are method and apparatus for cross retransmission between Grant-less Uplink transmission (GUL) and Scheduled Uplink transmission (SUL). An embodiment provides an apparatus for a user equipment (UE) comprising baseband circuitry including one or more processors to: encode an uplink (UL) transmission data for transmission to an evolved Node B (eNB) on an un-licensed spectrum; determine a mode of re-transmission for the UL transmission as a scheduled mode in which the re-transmission is based on a re-transmission grant derived from downlink control information (DCI) received from the eNB or a grant-less mode in which the re-transmission is performed without the re-transmission grant from the eNB; and encode the re-transmission of the UL transmission based on the determined mode. Also provided is hybrid automatic repeat request (HARQ) feedback for GUL and SUL. At least some embodiments allow for maximum channel occupancy time (MCOT) sharing.

CROSS REFERENCES TO RELATED APPLICATIONS

This application claims priority to International Application No.PCT/CN2017/076076 filed on Mar. 9, 2017, entitled “CROSS RETRANSMISSIONBETWEEN GRANTLESS UPLINK (GUL) AND SCHEDULED UPLINK (SUL)”, which isincorporated by reference herein in its entirety for all purposes.

TECHNICAL FIELD

Embodiments of the present disclosure generally relate to apparatusesand methods for wireless communications, and in particular to operationof wireless cellular systems in unlicensed spectrum.

BACKGROUND ART

Explosive wireless traffic growth has led to an urgent need of rateimprovement. With mature physical layer techniques, further improvementin the spectral efficiency may be marginal. On the other hand, thescarcity of licensed spectrum in low frequency band results in a deficitin data rate boost. Thus, there are emerging interests in the operationof wireless cellular systems in unlicensed spectrum.

SUMMARY

An embodiment of the disclosure provides User Equipment (UE) includingcircuitry configured to: encode an uplink (UL) transmission data fortransmission to a base station (e.g. an evolved Node B (eNB) or a nextgeneration node B (gNB)) on an unlicensed spectrum; determine a mode ofre-transmission for the UL transmission as one of: a scheduled mode inwhich the re-transmission is based on a re-transmission grant derivedfrom downlink control information (DCI) received from the eNB, and agrant-less mode in which the re-transmission is performed without there-transmission grant from the eNB; and encode the re-transmission ofthe UL transmission based on the determined mode.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the disclosure will be illustrated, by way of example andnot limitation, in the figures of the accompanying drawings in whichlike reference numerals refer to similar elements.

FIG. 1 is a diagram of an example environment in which apparatusesand/or methods described herein may be implemented.

FIG. 2 shows an illustrative scenario that may occur on an unlicensedspectrum in the environment of the disclosure.

FIG. 3 is a flow chart showing operations for Uplink (UL) transmissionand re-transmission in accordance with various embodiments of thedisclosure.

FIG. 4 shows an example Hybrid Automatic Repeat Request (HARQ) bitmap inaccordance with various embodiments of the disclosure.

FIG. 5 shows an example of organization of HARQ domain in accordancewith various embodiments of the disclosure.

FIG. 6 is a flow chart showing a method for UL re-transmission inaccordance with various embodiments of the disclosure.

FIG. 7 is a flowchart showing a method for UL re-transmission inaccordance with various embodiments of the disclosure.

FIG. 8 is a flowchart showing a method for UL re-transmission inaccordance with various embodiments of the disclosure.

FIG. 9 illustrates a general block diagram of a wireless communicationapparatus in accordance with various embodiments of the disclosure.

DETAILED DESCRIPTION OF EMBODIMENTS

Various aspects of the illustrative embodiments will be described usingterms commonly employed by those skilled in the art to convey thesubstance of their work to others skilled in the art. However, it willbe apparent to those skilled in the art that many alternate embodimentsmay be practiced using portions of the described aspects. For purposesof explanation, specific numbers, materials, and configurations are setforth in order to provide a thorough understanding of the illustrativeembodiments. However, it will be apparent to those skilled in the artthat alternate embodiments may be practiced without the specificdetails. In other instances, well known features may have been omittedor simplified in order to avoid obscuring the illustrative embodiments.

Further, various operations will be described as multiple discreteoperations, in turn, in a manner that is most helpful in understandingthe illustrative embodiments; however, the order of description shouldnot be construed as to imply that these operations are necessarily orderdependent. In particular, these operations need not be performed in theorder of presentation.

The phrase “in an embodiment” is used repeatedly herein. The phrasegenerally does not refer to the same embodiment; however, it may. Theterms “comprising,” “having,” and “including” are synonymous, unless thecontext dictates otherwise. The phrases “A or B” and “A/B” mean “(A),(B), or (A and B).”

One major enhancement in the 3rd Generation Partnership Project (3GPP)Release 13 has been to enable its operation in the unlicensed spectrumvia Licensed-Assisted Access (LAA), which expands the system bandwidthby utilizing the flexible carrier aggregation (CA) framework. Enhancedoperation of Long Term Evolution (LTE) systems in unlicensed spectrum isexpected in future releases and 5-th generation (5G) systems. PotentialLTE operation in unlicensed spectrum includes but is not limited to theLTE operation in the unlicensed spectrum via dual connectivity(DC)—known as DC-based LAA, and the standalone LTE system in theunlicensed spectrum, where LTE-based technology solely operates inunlicensed spectrum without requiring an “anchor” in licensed spectrum,known as MuLTEfire™ (or “MF”). MuLTEfire combines the performancebenefits of LTE technology with the simplicity of WiFi-like deploymentsand is envisioned as a significantly important technology component tomeet the ever-increasing wireless traffic. To enable the co-existence ofthe LTE radio nodes and other unlicensed nodes, a listen-before-talk(LBT) mechanism (also known as Clear Channel Assessment (CCA)) has alsobeen proposed in which the LTE radio node determines whether aparticular frequency channel is already occupied (e.g., by a WiFi node)before using the particular frequency channel. That is, with LBT, datamay only be transmitted when a channel is sensed to be idle.

In a MuLTEfire system, User Equipment (UE) may perform uplinktransmission of data under scheduling from a base station. This manneris referred to as Scheduling-based Uplink transmission (SUL) in thepresent disclosure. The UL data rate in this manner, however, is limitedfor two reasons. First the UE has to process the UL grant from the basestation, which involves a well-known 4 millisecond (ms) processing delayand limits the available UL frames at given transmission opportunities(TxOPs). Second, “double” LBT operations may be used since the basestation may perform LBT before transmitting Physical Downlink ControlChannel (PDCCH) and the UE also may perform LBT to acquire the channelfor data transmission.

Recently, Grant-less Uplink transmission (GUL) has been proposed toimprove the UL data rate, for example in MuLTEfire systems. GULtransmission may be performed using the frame structure ofSemi-Persistent Scheduling (SPS) transmission. GUL does not need to waitfor the UL grant from the base station and hence mitigates the delayresulted from the two reasons above. GUL allows a MuLTEfire system tohave higher probability to acquire the channel since both base stationand UE can perform independent LBT. However, GUL is initialized by theUE, and the re-transmission procedure as SPS cannot be reused (e.g.evolved Node B (eNodeB or eNB) or next generation node B (gNB) may notcorrectly detect the presence of GUL). This presents difficulties inhandling re-transmission in case of a failed UL transmission.

The present disclosure provides approaches to perform UL re-transmissionon unlicensed spectrum, e.g. in LTE-LAA or MuLTEfire systems. Inaccordance with some embodiments of the disclosure, a mode for ULre-transmission is determined as a scheduled mode based on a grant fromthe base station or a grant-less mode without such a grant. A pluralityof options are discussed in the present disclosure for making thisdetermination. HARQ mechanism may be used, and HARQ feedback isdiscussed for GUL and SUL. At least some embodiments of the disclosureallow for Maximum Channel Occupancy Time (MCOT) sharing.

FIG. 1 is a diagram of an example environment in which apparatusesand/or methods described herein may be implemented. As illustrated, inenvironment 100, a wireless network which may include core network (CN)120 and radio access network (RAN) 130 may provide network connectivityto User Equipment (UE) 110 and UE 112. The wireless network may provideUEs 110 and 112 with access to one or more external networks, such aspacket data network (PDN) 140. RAN 130 may be a 3GPP-based radio accessnetwork, e.g. an Evolved Universal Mobile Telecommunications System(UMTS) Terrestrial Radio Access (E-UTRA) based radio access network oranother type of radio access network. RAN 130 may be associated with anetwork operator that controls or otherwise manages CN 120. CN 120 mayinclude an Internet Protocol (IP)-based network.

UE 110 may include a portable computing and/or communication device,including but not limited to, a cellular phone, a laptop computer withconnectivity to a cellular wireless network, a tablet device, a personaldigital assistant (PDA), a gaming console, and the like. UE 110 may alsoinclude non-portable computing devices, e.g. a desktop computer,consumer or business appliances, or another device having an ability tobe wirelessly connected to RAN 130. In the following description,embodiments of the disclosure will be described in such context that UE110 is a cellular phone. UE 112 may be a device same as or similar to UE110.

In the context of the present disclosure, UE 110 may operate usingunlicensed spectrum, e.g. via LTE-LAA or MuLTEfire. For instance, UE 110may include radio circuitry capable of receiving a first carrier usinglicensed spectrum and a second carrier using unlicensed spectrumsimultaneously or alternately. The second carrier may be, for example, a5 GHz spectrum used by WiFi devices. Further, although FIG. 1 shows twoUEs 110 and 112 for simplicity, in practice there may be one or more UEsoperate in environment 100. The UEs additional to UE 110 and 112 may belegacy UEs that can operate only on licensed spectrum, or UEs that arecapable of utilizing the unlicensed spectrum.

RAN 130 may be a 3GPP access network that includes one or more radioaccess technologies (RATs). RAN 130 may include one or more basestations, for example eNB 132 and eNB 134. eNBs 132 and 134 may includeeNBs that provide coverage to a relatively large (macro cell) area or arelatively small (small cell) area. Small cells may be deployed toincrease system capacity by including a coverage area within a macrocell. Small cells may include picocells, femtocells, and/or home NodeBs.Small cells may, in some situations, be operated as Secondary Cells(SCells), in which the macro cell (known as the Primary Cell (PCell))may be used to exchange important control information and provide robustdata coverage and the SCell may be used as a secondary communicationchannel, such as to offload downlink data transmissions. The eNBs mayinclude one or more Remote Radio Heads (RRH), such as RRH 136. RRH 136can extend the coverage of an eNB by distributing the antenna system ofthe eNB. RRH 136 may be connected to eNB 132 by optical fiber (or byanother low-latency connection). The base stations may each includecircuitry to implement the operations discussed herein.

In the context of the present disclosure, the base stations may operateusing unlicensed spectrum, e.g. via LTE-LAA or MuLTEfire. For instance,eNB 132 may include radio circuitry capable of transmitting andreceiving both the first carrier using licensed spectrum and the secondcarrier using unlicensed spectrum.

Core network 120 may include an IP-based network. In the 3GPP networkarchitecture, CN 120 may include an Evolved Packet Core (EPC). Asillustrated, core network 120 may include Packet Data Network Gateway(PGW) 122, Serving Gateway (SGW) 124, and Mobility Management Entity(MME) 126. Although certain network devices are illustrated inenvironment 100 as being part of RAN 130 and core network 120, whether anetwork device is labeled as being in the “RAN” or the “core network” ofenvironment 100 may be an arbitrary decision that may not affect theoperation of wireless network.

PGW 122 may include one or more devices that act as the point ofinterconnect between core network 120 and external IP networks, such asPDN 140, and/or operator IP services. PGW 122 may route packets to RAN130 from the external IP networks, or from RAN 130 to the external IPnetworks. SGW 124 may include one or more network devices that aggregatetraffic received from eNBs 132 and/or 134. SGW 124 may generally handleuser plane traffic. MME 126 may include one or more computation andcommunication devices that perform operations to register UE 110 or 112with core network 120, establish bearer channels associated with asession with UE 110 or 112, hand off UE 110 or 112 from one eNB 132 toanother, and/or perform other operations. MME 126 may generally handlecontrol plane traffic.

PDN 140 may include one or more packet-based networks. PDN 140 mayinclude one or more external networks, such as a public network (e.g.,the Internet) or proprietary networks that provide services that areprovided by the operator of core network 120 (e.g., IP multimedia(IMS)-based services, transparent end-to-end packet-switched streamingservices (PSSs), or other services).

A number of interfaces are illustrated in FIG. 1. An interface may referto a physical or logical connection between devices in environment 100.The illustrated interfaces may be 3GPP standardized interfaces. Forexample, as illustrated, eNB 132 may communicate with SGW 124 and MME126 using the S1 interface (e.g., as defined by the 3GPP standards). eNB132 and eNB 134 may communicate with one another via the X2 interface.These interfaces are known to those skilled in the art and will not bedescribed in detail.

The quantity of devices and/or networks illustrated in FIG. 1 isprovided for explanatory purposes only. In practice, there may beadditional devices and/or networks, fewer devices and/or networks,different devices and/or networks, or differently arranged devicesand/or networks than illustrated in FIG. 1. Alternatively oradditionally, one or more of the devices of environment 100 may performone or more functions described as being performed by another one ormore of the devices of environment 100. Furthermore, while “direct”connections are shown in FIG. 1, these connections should be interpretedas logical communication pathways, and in practice, one or moreintervening devices (e.g., routers, gateways, modems, switches, hubs,etc.) may be present.

FIG. 2 shows an illustrative scenario 200 that may occur on anunlicensed spectrum in environment 100 of the present disclosure. Theunlicensed spectrum may be a 5 GHz frequency band for a WiFitransmission, for example. As shown in FIG. 2, transmissions of variousinformation may occur including WiFi transmission illustrated at 205,MuLTEfire (MF) downlink bursts illustrated at 210 and 245, MF uplinkbursts illustrated at 215 and 250, autonomous UL transmissions 225 and260 which may be Physical Uplink Shared Channel (PUSCH) or UL controlinformation from UEs (e.g. UEs 110 and 112), and DL control information230, 240 and 265 for the autonomous UL transmissions. In an embodiment,DL control information 230, 240 and 265 may include acknowledgement(ACK) or negative acknowledgement (NACK) for the UL transmissions and ULChannel State Information (CSI). FIG. 2 also illustrates LBT operations220, 235 and 255 performed prior to UL or DL transmissions. In anembodiment, LBT operations 220, 235 and 255 each may be category 4 ofthe LBT (Cat. 4 LBT), as provided in “3rd Generation PartnershipProject; Technical Specification Group Radio Access Network; Study onLicensed-Assisted Access to Unlicensed Spectrum; (Release 13)” (3GPP TR36.889 V13.0.0 (2015-06)).

FIG. 3 is a flow chart 300 showing operations for UL transmission andre-transmission in accordance with various embodiments of thedisclosure. The operations of FIG. 3 may be used for UE (e.g. UE 110) totransmit user plane or control plane data to a base station (e.g. eNB132), and may occur on unlicensed spectrum, e.g. in an LTE-LAA orMuLTEfire system. At 305, eNB 132 may perform LBT to sense if a desiredchannel is idle. As described above, the LBT may be a Cat. 4 LBT. eNB132 may process (e.g. modulate, encode, etc.) Downlink ControlInformation (DCI) and transmit the DCI to UE 110 on PDCCH at 310 if thechannel is sensed idle. The DCI may include information for scheduling aUL transmission to be performed by UE 110. UE 110 may receive andprocess (e.g. demodulate, decode, detect, etc.) the DCI, and prepare aUL frame in accordance with the scheduling of eNB 132 at 320.Subsequently or simultaneously, UE 110 may perform LBT at 325, which mayalso be a Cat. 4 LBT, to sense the availability of the channel. If thechannel is sensed idle, UE 110 may process (e.g. modulate, encode, etc.)and transmit the UL transmission data to eNB 132 at 330, for example onPUSCH. The UL transmission may be associated with a HARQ process number.Throughout the disclosure, transmission data or re-transmission data issometimes referred to as transmission or re-transmission for ease ofdescription.

At 340, eNB 132 may receive and process (e.g. demodulate, decode,detect, etc.) the UL transmission that UE 110 transmitted at 330, toextract data or control information therefrom. In accordance withvarious embodiments of the disclosure, eNB 132 may provide a feedback(e.g. modulate, encode, format, etc. feedback data for transmission) toUE 110 indicating whether the UL transmission has been successfullyreceived and/or demodulated. UE 110 may process (e.g. demodulate,decode, detect, etc.) the feedback to derive the feedback data. In anembodiment, the feedback may be a HARQ feedback, which may be includedin PDCCH encoded by eNB 132. For example, eNB 132 may, after performingan LBT operation at 345, send to UE 110 a HARQ bitmap at 350. The HARQbitmap may include a plurality of bits indicating ACK and NACK at eNB132 for the UL transmissions associated with corresponding HARQ processnumbers. FIG. 4 shows an example HARQ bitmap 400 including 8 bits, eachfor one HARQ process number. In the example of FIG. 4, bit “1” standsfor ACK, indicating that the UL transmission associated with that bithas been successfully demodulated, while bit “0” stands for NACK,indicating a failure of demodulating the associated UL transmission. Asshown in FIG. 4, the bit corresponding to HARQ process number 3 is “0”,indicating that eNB 132 fails to demodulate the UL transmissionassociated with this HARQ process number. The bits corresponding to HARQprocess numbers 0-2 and 4-7 are “1”, indicating ACK at eNB 132 for thecorresponding HARQ processes, and UE 110 may process and transmitsubsequent UL transmissions instead of a re-transmission.

In another embodiment, eNB 132 does not need to send an explicit ACKfeedback to UE 110 in case of a successful receipt and demodulation ofthe UL transmission; rather, eNB 132 may process and send DCI to UE 110,which includes a New Transmission ID (NDI) to schedule a next ULtransmission. The NDI may be a bit (0 or 1), and whether thetransmission corresponding to the NDI is successful may be indicated bywhether the bit is toggled (i.e. changed from 0 to 1 or from 1 to 0). Inan embodiment, eNB 132 may each time send a plurality of DCIs (e.g. 8DCIs) corresponding to a plurality of UL transmissions to UE 110.

If a NACK feedback is sent, i.e. eNB 132 fails to demodulate the ULtransmission, UE 110 may need to re-transmit the UL transmission. Inaccordance with various embodiments of the disclosure, UE 110 maydetermine a mode of re-transmission for the UL transmission as ascheduled mode (or “SUL re-transmission”) or a grant-less mode (or “GULre-transmission”), and process (e.g. modulate, encode, etc.) there-transmission of the UL transmission based on the determined mode. Inthe scheduled mode, the re-transmission is based on a re-transmissiongrant derived from DCI received from eNB 132, while in the grant-lessmode, the re-transmission is performed without the re-transmission grantfrom eNB 132. FIG. 3 generally shows that eNB 132 optionally sends there-transmission grant at 360 to UE 110 after an LBT operation 355, andthat UE 110 transmits the UL re-transmission at 370 to eNB 132 after anLBT operation 365. The UL re-transmission at 370 is an SULre-transmission if it is performed based on the re-transmission grant at360, and a GUL re-transmission if the re-transmission grant at 360 isabsent (e.g. the re-transmission is performed with an explicit HARQbitmap in DCI received from eNB 132). The detailed process ofdetermining the mode of re-transmission and performing there-transmission will be described later.

In the above description with reference to FIG. 3, UL transmission at330 is performed in the SUL manner since it follows the scheduling fromeNB 132 (sent at 310). However, FIG. 3 may also depicts UL transmissionin the GUL manner. For GUL transmission, the operations 305 and 310 areeliminated, and UE 110 performs the UL transmission at 330 autonomouslywithout the grant from eNB 132. The operations of UE 110 or eNB 132 inFIG. 3 may be performed, for example, by baseband circuitry of UE 110 orbaseband circuitry of eNB 132 as described later.

In some embodiments of the disclosure, UE 110 may determine the mode ofre-transmission as the scheduled mode if a HARQ process numberassociated with the UL transmission falls outside of a predefined group.In the embodiments, the domain of HARQ process numbers may be organizedsuch that only some of them are available for GUL re-transmission. FIG.5 shows an example of organization 500 of HARQ domain in accordance withvarious embodiments of the disclosure. In the example of FIG. 5, a groupof HARQ process numbers 0, 1, 2 and 3 each have a differentconfiguration from the other HARQ process numbers (e.g. configured witha bit “1” in contrast to “0” for the others) so that the ULtransmissions associated with these HARQ process numbers, if need to bere-transmitted (e.g. as indicated in the HARQ bitmap or by the NDI), maybe re-transmitted in the grant-less mode. In an embodiment, the factthat a HARQ process number falls within the group does not imply that aUL transmission associated therewith is necessarily to be re-transmittedin the grant-less mode; rather, UE 110 may determine the mode ofre-transmission as the grant-less mode or the scheduled mode dependingon other factors (e.g. in combination with the determinations describedlater). On the other hand, if a UL transmission associated with a HARQprocess number outside the group (e.g. No. 7 in the example of FIG. 5)needs to be re-transmitted, UE 110 will determine that it cannot bere-transmitted in the grant-less mode and the mode of re-transmissionshall be the scheduled mode.

The manner of organizing the domain of HARQ process numbers (i.e. whichHARQ process numbers should be put in the group and which not) maydepend on the implementation of the base station and is not limitedherein. In some embodiments, the group is configured by the base stationthrough dedicated or broadcast Radio Resource Control (RRC) signaling,which UE may receive and decode (e.g. demodulate, decode, detect, etc.).For example, eNB 132 may send to UE 110 an RRC message, in whichconfiguration data such as a sequence of bits “1111000000000000” isencoded, to configure UE 110 with the group of HARQ process numbers asshown in FIG. 5. When a UL transmission is indicated as NACK (e.g. inthe HARQ bitmap or by the NDI), if the HARQ process number associatedtherewith does not fall within the group of {0, 1, 2, 3}, UE 110 willdetermine the mode of re-transmission as the scheduled mode; otherwisethe mode of re-transmission can be determined as the grant-less mode,optionally taking other factors into consideration.

Though in FIG. 5, a bit “1” is used to indicate the members of the groupof HARQ process numbers associated with GUL re-transmission and “0” isused for the others, this is merely an example. It is also possible thata bit “0” is used to indicate the members of the group of HARQ processnumbers associated with GUL re-transmission while “1” for the others.Though 16 HARQ process numbers are configured in the example of FIG. 5,it is merely illustrative. Any number greater than 1 (e.g. 4, 8, 15,etc.) may be applied instead of 16. Though 4 HARQ process numbers areput in the group, it is also illustrative and the quantity may bechanged to other practical number, e.g. 1, 2 and the like. The numbersin the group are not necessarily consecutive. For example, the group maybe configured to include HARQ process numbers 1, 2, 6, or numbers 1, 3,5.

In some embodiments, SUL re-transmission may be provided with a higherpriority than GUL re-transmission. FIG. 6 is a flow chart 600 showing amethod for UL re-transmission in accordance with the embodiments of thedisclosure. Again, the operations of FIG. 6 may be used for UE (e.g. UE110) to transmit user plane or control plane data to a base station(e.g. eNB 132), and may occur on unlicensed spectrum, e.g. in an LTE-LAAor MuLTEfire system. The method starts at 610. At 620, UE 110 maytransmit a UL transmission to eNB 132 on an idle channel, similar to theUL transmission at 330 of FIG. 3. In an embodiment, the UL transmissionis a GUL transmission. At 630, UE 110 may receive and process a HARQfeedback from eNB 132 to determine whether the UL transmission has beensuccessfully received and/or demodulated. The HARQ feedback may be, forexample, a HARQ bitmap as discussed hereinbefore.

For the HARQ process numbers indicated as ACK in the HARQ feedback, UE110 may continue to perform GUL transmissions for subsequent data orcontrol information. In contrast, for the HARQ process numbers indicatedas NACK, eNB 132 may, when it has access to the channel (e.g. aftercompleting an LBT operation), transmit DCI to UE 110 as a UL grant toschedule a re-transmission. The DCI may be configured to assign a wholesystem bandwidth to UE 110 for re-transmission, or assign one of aplurality of orthogonal resources to one of a plurality of users toenable multiplexing.

Turning back to FIG. 6. UE 110 may maintain one or more timer for there-transmission. As an example, UE 110 may start a timer upon finishingthe UL transmission at 620, or upon receiving the HARQ feedback at 630.UE 110 may determine at 640 if the DCI has been received and the ULgrant has been derived within a certain period indicated by the timer.If so, UE 110 may determine the mode of re-transmission as the scheduledmode at 650 and perform the re-transmission in accordance withscheduling from eNB 132. On the other hand, when the timer expires at660 without receiving the UL grant, UE 110 may determine the mode ofre-transmission as the grant-less mode at 670 and perform there-transmission autonomously. The method ends at 680.

With the process described above, re-transmission may be triggered bythe timer. In other words, UE may wait for a certain period, which isdetermined by the timer, to receive grant from eNB 132 for an SULre-transmission. However, if no grant has been received when the timerexpires, UE 110 will perform a GUL re-transmission. The period for thetimer may be configured by eNB 132, or may be a predefined value. Themethod illustrated in FIG. 6 allows SUL re-transmission, which iscentrally controlled by eNB and has high reliability, to have a higherpriority than GUL re-transmission.

In an embodiment, UE 110 may maintain a single timer for there-transmission, and the timer may be shared by a plurality of HARQprocesses on UE 110. The timer may be reset each time UE 110 has newdata for GUL transmission, or may be reset only when all TransmissionBlocks (TBs) are new transmissions. In another embodiment, UE 110 maymaintain one or more timers each associated with a single HARQ process.Each of the timers may be set when the associated HARQ processcorresponds to a new initial transmission.

In an embodiment, UE 110 may maintain a timer for the HARQ feedback. Forexample, UE 110 may start the timer upon finishing the UL transmissionat 620, and if no HARQ feedback has been received from eNB 132 when thetimer expires, UE 110 may determine the mode of re-transmission as thegrant-less mode. The re-transmission may be performed for all the HARQprocesses for which no HARQ feedback has been received. Otherwise theembodiment may be identical to those described above with reference toFIG. 6.

Comparing FIG. 6 against FIG. 3, it can be found that the LBT operationsbefore transmission and re-transmission have been omitted. The LBToperations do exist in the practical process but are omitted in thedrawing for simplicity. This applies also for the processes shown in thelater drawings. Nevertheless, one or more LBT operations can be removedfrom the practical process, resulting in a reduced processing delay. Forexample, in FIG. 3, eNB 132 performs LBT at 345 before transmitting theHARQ feedback at 350. In an embodiment, eNB 132 may transmit the HARQfeedback in a shared MCOT of another UE, eliminating or shortening theLBT at 345. For example, another UE (e.g. UE 112) may perform a Cat. 4LBT to sense an idle channel and then transmit a PUSCH within its MCOT,while eNB 132 may utilize this MCOT to transmit the HARQ feedback to UE110. If the eNB determines that it will take a short period less than apredetermined first threshold (e.g. 16 ms) to transmit the HARQfeedback, the LBT may be eliminated. If it will take a medium periodmore than the first threshold but still less than a predetermined secondthreshold (e.g. 25 ms), eNB 132 may perform a short type LBT instead ofthe Cat. 4 LBT. However, if it will take a period more than the secondthreshold, eNB may perform the Cat. 4 LBT normally.

Though in the above discussion on MCOT sharing, the HARQ feedback istaken as the example, it should not be taken in a limiting sense; eNB132 may perform transmission of other information (e.g. DCI, forscheduling DL or UL transmission or re-transmission) to UE 110 in theMCOT of UE 112, without the LBT or with a shorter LBT. Further, theconcept of MCOT sharing is not limited to the process of FIG. 6, but maybe applied in other processes described herein. MCOT sharing allows fora reduced latency and enables UE to prepare the next transmission inadvance.

In some embodiments, the re-transmission may be made opportunistic. FIG.7 is a flow chart 700 showing a method for UL re-transmission inaccordance with the embodiments of the disclosure. The method of FIG. 7may be used for UE (e.g. UE 110) to transmit user plane or control planedata to a base station (e.g. eNB 132), and may occur on unlicensedspectrum, e.g. in an LTE-LAA or MuLTEfire system. The method starts at710. UE 110 may transmit a UL transmission, either GUL or SUL, to eNB132 at 720, and may receive and process a HARQ feedback from eNB 132 at730 to determine whether the UL transmission has been successfullyreceived and/or demodulated. The operations at 720 and 730 may besimilar or identical to the operations at 620 and 630 in FIG. 6,respectively. For example, UE 110 may transmit UL transmissionsassociated with HARQ process numbers 0 and 1 in SUL manner and ULtransmissions associated with HARQ process numbers 2, 3, 4 and 5 in GULmanner at 720, and then receive a HARQ feedback at 730 indicating NACKfor the HARQ process number 1 as well as ACK for the other HARQ processnumbers.

At 740, a determination is made as to which of eNB 132 and UE 110acquires an idle channel first. If eNB 132 acquires the channel first,i.e. earlier than UE 110, the mode of re-transmission may be determinedas the scheduled mode at 750. However, if UE 110 acquires the channelearlier than eNB 132, UE 110 may determine the mode of re-transmissionas the grant-less mode at 760. For the example mentioned above, if eNB132 acquires the channel first, it may transmit DCI to UE 110 toschedule a re-transmission for HARQ process number 1; whereas if UE 110acquires the channel first, it may perform a GUL re-transmission withoutwaiting for the grant from eNB 132. In this way, regardless of themodality of transmission (GUL or SUL), once the HARQ feedback isreceived, UE will perform a re-transmission in the modality that ensuresthe lowest latency. Method 700 ends at 770.

In some embodiments, UE may maintain a timer to address there-transmission of GUL. FIG. 8 is a flowchart 800 showing a method forUL re-transmission in accordance with the embodiments of the disclosure.The method starts at 810. UE 110 may transmit at 820 a UL transmissionto eNB 132 on an idle channel. The UL transmission may be a GULtransmission. UE 110 may start a timer upon finishing the ULtransmission, and determine whether a HARQ feedback for the ULtransmission has been received from eNB 132 at 830 while the timercounts down. If UE 110 receives the HARQ feedback before the expirationof the timer, at 840 UE 110 may process the HARQ feedback and, ifneeded, perform re-transmission, as illustrated in FIG. 6 above.However, if UE 110 determines that no HARQ feedback has been receivedwhen the timer expires at 850, UE 110 may interpret this as eNB 132 hasnot detected the GUL transmission, and may reset the corresponding HARQprocess numbers instead of keep waiting. Therefore, at 860 UE 110 maytransmit a packet same as the UL transmission at 820, but as a newtransmission, since eNB 132 did not detect the previous UL transmission.Alternatively, UE 110 may perform a re-transmission for the ULtransmission at 860, e.g. as a GUL re-transmission.

The new transmission or re-transmission at 860 may not necessarily besuccessfully received at eNB 132. In further embodiments, UE 110 maymake a predetermined number (N) of attempts of the new transmission orthe re-transmission. If it is determined at 870 that the outcome is thesame (e.g. no HARQ feedback is timely received) after these attempts, UE110 may reset at 880 the HARQ process number associated with the ULtransmission, e.g. by HARQ refreshing. The method ends at 890.

As used herein, the term “circuitry” may refer to, be part of, orinclude an Application Specific Integrated Circuit (ASIC), an electroniccircuit, a processor (shared, dedicated, or group), and/or memory(shared, dedicated, or group) that execute one or more software orfirmware programs, a combinational logic circuit, and/or other suitablehardware components that provide the described functionality. In someembodiments, the circuitry may be implemented in, or functionsassociated with the circuitry may be implemented by, one or moresoftware or firmware modules. In some embodiments, circuitry may includelogic, at least partially operable in hardware.

Embodiments described herein may be implemented into an apparatus usingany suitably configured hardware and/or software. FIG. 9 illustrates ageneral block diagram of a wireless communication apparatus 900 inaccordance with various embodiments of the disclosure. In embodiments,the apparatus 900 may be, implement, be incorporated into, or otherwisebe a part of a user equipment (UE), an evolved NodeB (eNB), and/or someother electronic device. In some embodiments, the apparatus 900 mayinclude application circuitry 902, baseband circuitry 904, RadioFrequency (RF) circuitry 906, front-end module (FEM) circuitry 908 andone or more antennas 910, coupled together at least as shown. Inembodiments where the apparatus 900 is implemented in or by an eNB, theapparatus 900 may also include network interface circuitry (not shown)for communicating over a wired interface (for example, an X2 interface,an S1 interface, and the like).

The application circuitry 902 may include one or more applicationprocessors. For example, the application circuitry 902 may includecircuitry such as, but not limited to, one or more single-core ormulti-core processors 902 a. The processor(s) 902 a may include anycombination of general-purpose processors and dedicated processors(e.g., graphics processors, application processors, etc.). Theprocessors 902 a may be coupled with and/or may includecomputer-readable media 902 b (also referred to as “CRM 902 b”, “memory902 b”, “storage 902 b”, or “memory/storage 902 b”) and may beconfigured to execute instructions stored in the CRM 902 b to enablevarious applications and/or operating systems to run on the system.

The baseband circuitry 904 may include circuitry such as, but notlimited to, one or more single-core or multi-core processors. Thebaseband circuitry 904 may include one or more baseband processorsand/or control logic to process baseband signals received from a receivesignal path of the RF circuitry 906 and to generate baseband signals fora transmit signal path of the RF circuitry 906. Baseband circuity 904may interface with the application circuitry 902 for generation andprocessing of the baseband signals and for controlling operations of theRF circuitry 906. For example, in some embodiments, the basebandcircuitry 904 may include a second generation (2G) baseband processor904 a, third generation (3G) baseband processor 904 b, fourth generation(4G) baseband processor 904 c, and/or other baseband processor(s) 904 dfor other existing generations, generations in development or to bedeveloped in the future (e.g., fifth generation (5G), 6G, etc.). Thebaseband circuitry 904 (e.g., one or more of baseband processors 904a-d) may handle various radio control functions that enablecommunication with one or more radio networks via the RF circuitry 906.The radio control functions may include, but are not limited to, signalmodulation/demodulation, encoding/decoding, radio frequency shifting,and the like. In some embodiments, modulation/demodulation circuitry ofthe baseband circuitry 904 may include Fast-Fourier Transform (FFT),precoding, and/or constellation mapping/demapping functionality. In someembodiments, encoding/decoding circuitry of the baseband circuitry 904may include convolution, tail-biting convolution, turbo, Viterbi, and/orLow Density Parity Check (LDPC) encoder/decoder functionality.Embodiments of modulation/demodulation and encoder/decoder functionalityare not limited to these examples and may include other suitablefunctionality in other embodiments.

In some embodiments, the baseband circuitry 904 may include elements ofa protocol stack such as, for example, elements of an evolved universalterrestrial radio access network (E-UTRAN) protocol including, forexample, physical (PHY), media access control (MAC), radio link control(RLC), packet data convergence protocol (PDCP), and/or radio resourcecontrol (RRC) elements. A central processing unit (CPU) 904 e of thebaseband circuitry 904 may be configured to run elements of the protocolstack for signaling of the PHY, MAC, RLC, PDCP and/or RRC layers. Insome embodiments, the baseband circuitry may include one or more audiodigital signal processor(s) (DSP) 904 f. The audio DSP(s) 904 f mayinclude elements for compression/decompression and echo cancellation andmay include other suitable processing elements in other embodiments. Thebaseband circuitry 904 may further include computer-readable media 904 g(also referred to as “CRM 904 g”, “memory 904 g”, “storage 904 g”, or“CRM 904 g”). The CRM 904 g may be used to load and store data and/orinstructions for operations performed by the processors of the basebandcircuitry 904. CRM 904 g for one embodiment may include any combinationof suitable volatile memory and/or non-volatile memory. The CRM 904 gmay include any combination of various levels of memory/storageincluding, but not limited to, read-only memory (ROM) having embeddedsoftware instructions (e.g., firmware), random access memory (e.g.,dynamic random access memory (DRAM)), cache, buffers, etc.). The CRM 904g may be shared among the various processors or dedicated to particularprocessors. Components of the baseband circuitry 904 may be suitablycombined in a single chip, a single chipset, or disposed on a samecircuit board in some embodiments. In some embodiments, some or all ofthe constituent components of the baseband circuitry 904 and theapplication circuitry 902 may be implemented together, such as, forexample, on a system on a chip (SOC).

In some embodiments, the baseband circuitry 904 may provide forcommunication compatible with one or more radio technologies. Forexample, in some embodiments, the baseband circuitry 904 may supportcommunication with an E-UTRAN and/or other wireless metropolitan areanetworks (WMAN), a wireless local area network (WLAN), a wirelesspersonal area network (WPAN). Embodiments in which the basebandcircuitry 904 is configured to support radio communications of more thanone wireless protocol may be referred to as multi-mode basebandcircuitry.

RF circuitry 906 may enable communication with wireless networks usingmodulated electromagnetic radiation through a non-solid medium. Invarious embodiments, the RF circuitry 906 may include switches, filters,amplifiers, etc., to facilitate the communication with the wirelessnetwork. RF circuitry 906 may include a receive signal path that mayinclude circuitry to down-convert RF signals received from the FEMcircuitry 908 and provide baseband signals to the baseband circuitry904. RF circuitry 906 may also include a transmit signal path that mayinclude circuitry to up-convert baseband signals provided by thebaseband circuitry 904 and provide RF output signals to the FEMcircuitry 908 for transmission.

In some embodiments, the RF circuitry 906 may include a receive signalpath and a transmit signal path. The receive signal path of the RFcircuitry 906 may include mixer circuitry 906 a, amplifier circuitry 906b and filter circuitry 906 c. The transmit signal path of the RFcircuitry 906 may include filter circuitry 906 c and mixer circuitry 906a. RF circuitry 906 may also include synthesizer circuitry 906 d forsynthesizing a frequency for use by the mixer circuitry 906 a of thereceive signal path and the transmit signal path. In some embodiments,the mixer circuitry 906 a of the receive signal path may be configuredto down-convert RF signals received from the FEM circuitry 908 based onthe synthesized frequency provided by synthesizer circuitry 906 d. Theamplifier circuitry 906 b may be configured to amplify thedown-converted signals and the filter circuitry 906 c may be a low-passfilter (LPF) or band-pass filter (BPF) configured to remove unwantedsignals from the down-converted signals to generate output basebandsignals. Output baseband signals may be provided to the basebandcircuitry 904 for further processing. In some embodiments, the outputbaseband signals may be zero-frequency baseband signals, although thisis not a requirement. In some embodiments, mixer circuitry 906 a of thereceive signal path may comprise passive mixers, although the scope ofthe embodiments is not limited in this respect.

In some embodiments, the mixer circuitry 906 a of the transmit signalpath may be configured to up-convert input baseband signals based on thesynthesized frequency provided by the synthesizer circuitry 906 d togenerate RF output signals for the FEM circuitry 908. The basebandsignals may be provided by the baseband circuitry 904 and may befiltered by filter circuitry 906 c. The filter circuitry 906 c mayinclude a low-pass filter (LPF), although the scope of the embodimentsis not limited in this respect.

In some embodiments, the mixer circuitry 906 a of the receive signalpath and the mixer circuitry 906 a of the transmit signal path mayinclude two or more mixers and may be arranged for quadraturedownconversion and/or upconversion, respectively. In some embodiments,the mixer circuitry 906 a of the receive signal path and the mixercircuitry 906 a of the transmit signal path may include two or moremixers and may be arranged for image rejection (e.g., Hartley imagerejection). In some embodiments, the mixer circuitry 906 a of thereceive signal path and the mixer circuitry 906 a of the transmit signalpath may be arranged for direct downconversion and/or directupconversion, respectively. In some embodiments, the mixer circuitry 906a of the receive signal path and the mixer circuitry 906 a of thetransmit signal path may be configured for super-heterodyne operation.

In some embodiments, the output baseband signals and the input basebandsignals may be analog baseband signals, although the scope of theembodiments is not limited in this respect. In some alternateembodiments, the output baseband signals and the input baseband signalsmay be digital baseband signals. In these alternate embodiments, the RFcircuitry 906 may include analog-to-digital converter (ADC) anddigital-to-analog converter (DAC) circuitry and the baseband circuitry904 may include a digital baseband interface to communicate with the RFcircuitry 906.

In some dual-mode embodiments, a separate radio IC circuitry may beprovided for processing signals for each spectrum, although the scope ofthe embodiments is not limited in this respect.

In some embodiments, the synthesizer circuitry 906 d may be afractional-N synthesizer or a fractional N/N+1 synthesizer, although thescope of the embodiments is not limited in this respect, as other typesof frequency synthesizers may be suitable. For example, synthesizercircuitry 906 d may be a delta-sigma synthesizer, a frequencymultiplier, or a synthesizer comprising a phase-locked loop with afrequency divider. The synthesizer circuitry 906 d may be configured tosynthesize an output frequency for use by the mixer circuitry 906 a ofthe RF circuitry 906 based on a frequency input and a divider controlinput. In some embodiments, the synthesizer circuitry 906 d may be afractional N/N+1 synthesizer.

In some embodiments, frequency input may be provided by a voltagecontrolled oscillator (VCO), although that is not a requirement. Dividercontrol input may be provided by either the baseband circuitry 904 orthe application circuitry 902 depending on the desired output frequency.In some embodiments, a divider control input (e.g., N) may be determinedfrom a look-up table based on a channel indicated by the applicationcircuitry 902.

Synthesizer circuitry 906d of the RF circuitry 906 may include adivider, a delay-locked loop (DLL), a multiplexer and a phaseaccumulator. In some embodiments, the divider may be a dual modulusdivider (DMD) and the phase accumulator may be a digital phaseaccumulator (DPA). In some embodiments, the DMD may be configured todivide the input signal by either N or N+1 (e.g., based on a carry out)to provide a fractional division ratio. In some example embodiments, theDLL may include a set of cascaded, tunable, delay elements, a phasedetector, a charge pump and a D-type flip-flop. In these embodiments,the delay elements may be configured to break a VCO period up into Ndequal packets of phase, where Nd is the number of delay elements in thedelay line. In this way, the DLL provides negative feedback to helpensure that the total delay through the delay line is one VCO cycle.

In some embodiments, synthesizer circuitry 906 d may be configured togenerate a carrier frequency as the output frequency, while in otherembodiments, the output frequency may be a multiple of the carrierfrequency (e.g., twice the carrier frequency, four times the carrierfrequency) and used in conjunction with quadrature generator and dividercircuitry to generate multiple signals at the carrier frequency withmultiple different phases with respect to each other. In someembodiments, the output frequency may be a LO frequency (fLO). In someembodiments, the RF circuitry 906 may include an IQ/polar converter.

FEM circuitry 908 may include a receive signal path that may includecircuitry configured to operate on RF signals received from one or moreantennas 910, amplify the received signals and provide the amplifiedversions of the received signals to the RF circuitry 906 for furtherprocessing. FEM circuitry 908 may also include a transmit signal paththat may include circuitry configured to amplify signals fortransmission provided by the RF circuitry 906 for transmission by one ormore of the one or more antennas 910. In some embodiments, the FEMcircuitry 908 may include a TX/RX switch to switch between transmit modeand receive mode operation. The FEM circuitry 908 may include a receivesignal path and a transmit signal path. The receive signal path of theFEM circuitry may include a low-noise amplifier (LNA) to amplifyreceived RF signals and provide the amplified received RF signals as anoutput (e.g., to the RF circuitry 906). The transmit signal path of theFEM circuitry 908 may include a power amplifier (PA) to amplify input RFsignals (e.g., provided by RF circuitry 906), and one or more filters togenerate RF signals for subsequent transmission (e.g., by one or more ofthe one or more antennas 910).

In some embodiments, the apparatus 900 may include additional elementssuch as, for example, a display, a camera, one or more sensors, and/orinterface circuitry (for example, input/output (I/O) interfaces orbuses) (not shown). In embodiments where the apparatus is implemented inor by an eNB, the apparatus 900 may include network interface circuitry.The network interface circuitry may be one or more computer hardwarecomponents that connect apparatus 900 to one or more network elements,such as one or more servers within a core network or one or more othereNBs via a wired connection. To this end, the network interfacecircuitry may include one or more dedicated processors and/or fieldprogrammable gate arrays (FPGAs) to communicate using one or morenetwork communications protocols such as X2 application protocol (AP),S1 AP, Stream Control Transmission Protocol (SCTP), Ethernet,Point-to-Point (PPP), Fiber Distributed Data Interface (FDDI), and/orany other suitable network communications protocols.

In some embodiments, the apparatus of FIG. 9 may be configured toperform one or more processes, techniques, and/or methods as describedherein, or portions thereof.

The following paragraphs describe examples of various embodiments.

Example 1 includes an apparatus for a user equipment (UE), whichincludes baseband circuitry including one or more processors to: encodean uplink (UL) transmission data for transmission to an evolved Node B(eNB) on an unlicensed spectrum; determine a mode of re-transmission forthe UL transmission as one of: a scheduled mode in which there-transmission is based on a re-transmission grant derived fromdownlink control information (DCI) received from the eNB, and agrant-less mode in which the re-transmission is performed without there-transmission grant from the eNB; and encode the re-transmission ofthe UL transmission based on the determined mode.

Example 2 includes the apparatus of Example 1, wherein the basebandcircuitry is further configured to: decode a hybrid automatic repeatrequest (HARQ) feedback received from the eNB; and determine the mode ofre-transmission in response to the HARQ feedback indicating a negativeacknowledgement (NACK) at the eNB of the UL transmission.

Example 3 includes the apparatus of Example 2, wherein the basebandcircuitry is to further: determine the mode of re-transmission as thescheduled mode if a HARQ process number associated with the ULtransmission falls outside of a predefined group.

Example 4 includes the apparatus of Example 3, wherein the basebandcircuitry is to further: decode dedicated or broadcast radio resourcecontrol (RRC) signaling to configure the group.

Example 5 includes the apparatus of Example 2, wherein the HARQ feedbackincludes a HARQ bitmap indicating acknowledgement (ACK) and NACK at theeNB for a plurality of UL transmissions associated with correspondingHARQ process numbers.

Example 6 includes the apparatus of Example 5, wherein the basebandcircuitry is to further: encode another UL transmission data in responseto the HARQ feedback indicating an ACK at the eNB of the ULtransmission.

Example 7 includes the apparatus of any of Examples 1-6, wherein thebaseband circuitry is to further: start a timer upon finishing the ULtransmission; and determine the mode of re-transmission as the scheduledmode if the re-transmission grant is derived before expiration of thetimer, and as the grant-less mode when the timer expires without there-transmission grant.

Example 8 includes the apparatus of Example 7, wherein the basebandcircuitry is to further: determine the mode of re-transmission as thegrant-less mode when the timer expires without receiving a hybridautomatic repeat request (HARQ) feedback from the eNB.

Example 9 includes the apparatus of Example 2, wherein the basebandcircuitry is to further: start a timer upon receiving the HARQ feedback;and determine the mode of re-transmission as the scheduled mode if there-transmission grant is derived before expiration of the timer, and asthe grant-less mode when the timer expires without the re-transmissiongrant.

Example 10 includes the apparatus of Example 9, wherein the timer isshared by a plurality of HARQ processes on the UE.

Example 11 includes the apparatus of Example 9, wherein the timer isassociated with a single HARQ process associated with the ULtransmission.

Example 12 includes the apparatus of any of Examples 1-11, wherein theDCI is configured to assign to the UE a whole system bandwidth or one ofa plurality of orthogonal resources.

Example 13 includes the apparatus of any of Examples 1-12, wherein thebaseband circuitry is to further: determine the mode of re-transmissionas the scheduled mode if the eNB acquires a channel earlier than the UE,and as the grant-less mode if the UE acquires the channel earlier thanthe eNB.

Example 14 includes the apparatus of any of Examples 1-13, wherein thebaseband circuitry is to further: perform a clear channel assessment(CCA) before transmitting the UL transmission and before there-transmission.

Example 15 includes the apparatus of any of Examples 1-14, wherein thebaseband circuitry is to further: encode the UL transmission data fortransmission on physical uplink shared channel (PUSCH).

Example 16 includes the apparatus of any of Examples 1-15, wherein thebaseband circuitry is to further: encode the UL transmission data fortransmission as a grant-less uplink (GUL) transmission.

Example 17 includes an apparatus for a user equipment (UE), whichincludes baseband circuitry including one or more processors: transmitan uplink (UL) transmission to an evolved Node B (eNB) on an unlicensedspectrum; start a timer upon finishing the UL transmission; and when thetimer expires without receiving a hybrid automatic repeat request (HARQ)feedback from the eNB for the UL transmission, perform one of:transmitting, as a new transmission, a packet same as the ULtransmission, and performing a re-transmission for the UL transmission.

Example 18 includes the apparatus of Example 17, wherein the basebandcircuitry is to further: reset a HARQ process number associated with theUL transmission.

Example 19 includes the apparatus of Example 18, wherein the basebandcircuitry is to further: make a predetermined number of attempts of thenew transmission or the re-transmission before resetting the HARQprocess number.

Example 20 includes an apparatus of an evolved Node B (eNB), whichincludes baseband circuitry including one or more processors to: decodeuplink (UL) transmission data received from user equipment (UE) on anunlicensed spectrum; and encode a hybrid automatic repeat request (HARQ)feedback for the UE, wherein the HARQ feedback includes a HARQ bitmapindicating acknowledgement (ACK) and negative acknowledgement (NACK) atthe eNB for the UL transmissions associated with corresponding HARQprocess numbers.

Example 21 includes the apparatus of Example 20, wherein the basebandcircuitry is to further: encode downlink control information (DCI) fortransmission to the UE to schedule a re-transmission of one or more ofthe UL transmission indicated as NACK in the HARQ bitmap.

Example 22 includes the apparatus of Example 20 or 21, wherein thebaseband circuitry is to further: encode configuration data for the UEto configure the UE with a group of HARQ process numbers throughdedicated or broadcast radio resource control (RRC) signaling, whereinif a UL transmission indicated as NACK is associated with a HARQ processnumber falling within the group, a re-transmission of the ULtransmission can be performed without a re-transmission grant from theeNB.

Example 23 includes the apparatus of any of Examples 20-22, wherein thebaseband circuitry is to further: encode the HARQ feedback fortransmission to the UE during a maximum channel occupancy time (MCOT) ofa second UE different from the UE.

Example 24 includes the apparatus of Example 21, wherein the DCI is tobe transmitted to the UE during a maximum channel occupancy time (MCOT)of a second UE different from the UE.

Example 25 includes the apparatus of Example 21, wherein the DCI isconfigured to assign to the UE a whole system bandwidth or one of aplurality of orthogonal resources.

Example 26 includes the apparatus of any of Examples 20-25, wherein thebaseband circuitry is to further: encode physical downlink controlchannel (PDCCH) to include the HARQ feedback.

Example 27 includes the apparatus of any of Examples 20-26, wherein thebaseband circuitry is to further: perform a clear channel assessment(CCA) before transmitting the HARQ feedback.

Example 28 includes a method performed at a user equipment (UE),including: encoding an uplink (UL) transmission data for transmission toan evolved Node B (eNB) on an unlicensed spectrum; determining a mode ofre-transmission for the UL transmission as one of: a scheduled mode inwhich the re-transmission is based on a re-transmission grant derivedfrom downlink control information (DCI) received from the eNB, and agrant-less mode in which the re-transmission is performed without there-transmission grant from the eNB; and encoding the re-transmission ofthe UL transmission based on the determined mode.

Example 29 includes the method of Example 28, and further includes:decoding a hybrid automatic repeat request (HARQ) feedback received fromthe eNB; and determining the mode of re-transmission in response to theHARQ feedback indicating a negative acknowledgement (NACK) at the eNB ofthe UL transmission.

Example 30 includes the method of Example 29, wherein the mode ofre-transmission is determined as the scheduled mode if a HARQ processnumber associated with the UL transmission falls outside of a predefinedgroup.

Example 31 includes the method of Example 30, wherein the group isconfigured by the eNB through dedicated or broadcast radio resourcecontrol (RRC) signaling.

Example 32 includes the method of Example 29, wherein the HARQ feedbackincludes a HARQ bitmap indicating acknowledgement (ACK) and NACK at theeNB for a plurality of UL transmissions associated with correspondingHARQ process numbers.

Example 33 includes the method of Example 32, and further includes:encoding another UL transmission data in response to the HARQ feedbackindicating an ACK at the eNB of the UL transmission.

Example 34 includes the method of any of Examples 28-33, and furtherincludes: starting a timer upon finishing the UL transmission; anddetermining the mode of re-transmission as the scheduled mode if there-transmission grant is derived before expiration of the timer, and asthe grant-less mode when the timer expires without the re-transmissiongrant.

Example 35 includes the method of Example 34, and further includes:determining the mode of re-transmission as the grant-less mode when thetimer expires without receiving a hybrid automatic repeat request (HARQ)feedback from the eNB.

Example 36 includes the method of Example 29, and further includes:starting a timer upon receiving the HARQ feedback; and determining themode of re-transmission as the scheduled mode if the re-transmissiongrant is derived before expiration of the timer, and as the grant-lessmode when the timer expires without the re-transmission grant.

Example 37 includes the method of Example 36, wherein the timer isshared by a plurality of HARQ processes on the UE.

Example 38 includes the method of Example 36, wherein the timer isassociated with a single HARQ process associated with the ULtransmission.

Example 39 includes the method of any of Examples 28-38, wherein the DCIis configured to assign to the UE a whole system bandwidth or one of aplurality of orthogonal resources.

Example 40 includes the method of any of Examples 28-39, wherein themode of re-transmission is determined as the scheduled mode if the eNBacquires a channel earlier than the UE, and as the grant-less mode ifthe UE acquires the channel earlier than the eNB.

Example 41 includes the method of any of Examples 28-40, and furtherincludes: performing a clear channel assessment (CCA) beforetransmitting the UL transmission and before the re-transmission.

Example 42 includes the method of any of Examples 28-41, and furtherincludes: encoding the UL transmission data for transmission on physicaluplink shared channel (PUSCH).

Example 43 includes the method of any of Examples 28-42, and furtherincludes: encoding the UL transmission data for transmission as agrant-less uplink (GUL) transmission.

Example 44 includes a method performed at a user equipment (UE),including: transmitting an uplink (UL) transmission to an evolved Node B(eNB) on an unlicensed spectrum; starting a timer upon finishing the ULtransmission; and when the timer expires without receiving a hybridautomatic repeat request (HARQ) feedback from the eNB for the ULtransmission, performing one of: transmitting, as a new transmission, apacket same as the UL transmission, and performing a re-transmission forthe UL transmission.

Example 45 includes the method of Example 44, and further includes:resetting a HARQ process number associated with the UL transmission.

Example 46 includes the method of Example 45, and further includes:making a predetermined number of attempts of the new transmission or there-transmission before resetting the HARQ process number.

Example 47 includes a method performed at an evolved Node B (eNB),including: decoding uplink (UL) transmission data received from userequipment (UE) on an unlicensed spectrum; and encoding a hybridautomatic repeat request (HARQ) feedback for the UE, wherein the HARQfeedback includes a HARQ bitmap indicating acknowledgement (ACK) andnegative acknowledgement (NACK) at the eNB for the UL transmissionsassociated with corresponding HARQ process numbers.

Example 48 includes the method of Example 47, and further includes:encoding downlink control information (DCI) for transmission to the UEto schedule a re-transmission of one or more of the UL transmissionindicated as NACK in the HARQ bitmap.

Example 49 includes the method of Example 47 or 48, and furtherincludes: encoding configuration data for the UE to configure the UEwith a group of HARQ process numbers through dedicated or broadcastradio resource control (RRC) signaling, wherein if a UL transmissionindicated as NACK is associated with a HARQ process number fallingwithin the group, a re-transmission of the UL transmission can beperformed without a re-transmission grant from the eNB.

Example 50 includes the method of any of Examples 47-50, and furtherincludes encoding the HARQ feedback for transmission to the UE during amaximum channel occupancy time (MCOT) of a second UE different from theUE.

Example 51 includes the method of Example 48, wherein the DCI is to betransmitted to the UE during a maximum channel occupancy time (MCOT) ofa second UE different from the UE.

Example 52 includes the method of Example 48, wherein the DCI isconfigured to assign to the UE a whole system bandwidth or one of aplurality of orthogonal resources.

Example 53 includes the method of any of Examples 47-52, and furtherincludes encoding physical downlink control channel (PDCCH) to includethe HARQ feedback.

Example 54 includes the method of any of Examples 47-53, and furtherincludes performing a clear channel assessment (CCA) before transmittingthe HARQ feedback.

Example 55 includes a non-transitory computer-readable medium havinginstructions stored thereon, the instructions when executed by one ormore processor(s) causing the processor(s) to perform the method of anyof Examples 28-54.

Example 56 includes an apparatus for user equipment (UE), includingmeans for performing the actions of the method of any of Examples 28-46.

Example 57 includes an apparatus for an evolved Node B (eNB), includingmeans for performing the actions of the method of any of Examples 47-54.

Example 58 includes User equipment (UE) as shown and described in thedescription.

Example 59 includes an evolved Node B (eNB) as shown and described inthe description.

Example 60 includes a method performed at user equipment (UE) as shownand described in the description.

Example 61 includes a method performed at an evolved Node B (eNB) asshown and described in the description.

Although certain embodiments have been illustrated and described hereinfor purposes of description, a wide variety of alternate and/orequivalent embodiments or implementations calculated to achieve the samepurposes may be substituted for the embodiments shown and describedwithout departing from the scope of the present disclosure. Thisapplication is intended to cover any adaptations or variations of theembodiments discussed herein. Therefore, it is manifestly intended thatembodiments described herein be limited only by the appended claims andthe equivalents thereof.

1.-25. (canceled)
 26. An apparatus for a user equipment (UE),comprising: baseband circuitry including one or more processors to:encode an uplink (UL) transmission data for transmission to an evolvedNode B (eNB) on an unlicensed spectrum; determine a mode ofre-transmission for the UL transmission as one of: a scheduled mode inwhich the re-transmission is based on a re-transmission grant derivedfrom downlink control information (DCI) received from the eNB, and agrant-less mode in which the re-transmission is performed without there-transmission grant from the eNB; and encode the re-transmission ofthe UL transmission based on the determined mode.
 27. The apparatus ofclaim 26, wherein the baseband circuitry is further configured to:decode a hybrid automatic repeat request (HARQ) feedback received fromthe eNB; and determine the mode of re-transmission in response to theHARQ feedback indicating a negative acknowledgement (NACK) at the eNB ofthe UL transmission.
 28. The apparatus of claim 27, wherein the basebandcircuitry is to further: determine the mode of re-transmission as thescheduled mode if a HARQ process number associated with the ULtransmission falls outside of a predefined group.
 29. The apparatus ofclaim 28, wherein baseband circuitry is to further: decode dedicated orbroadcast radio resource control (RRC) signaling to configure the group.30. The apparatus of claim 27, wherein the HARQ feedback comprises aHARQ bitmap indicating acknowledgement (ACK) and NACK at the eNB for aplurality of UL transmissions associated with corresponding HARQ processnumbers.
 31. The apparatus of claim 30, wherein the baseband circuitryis to further: encode another UL transmission data in response to theHARQ feedback indicating an ACK at the eNB of the UL transmission. 32.The apparatus of claim 26, wherein the baseband circuitry is to further:start a timer upon finishing the UL transmission; and determine the modeof re-transmission as the scheduled mode if the re-transmission grant isderived before expiration of the timer, and as the grant-less mode whenthe timer expires without the re-transmission grant.
 33. The apparatusof claim 32, wherein the baseband circuitry is to further determine themode of re-transmission as the grant-less mode when the timer expireswithout receiving a hybrid automatic repeat request (HARQ) feedback fromthe eNB.
 34. The apparatus of claim 27, wherein the baseband circuitryis to further: start a timer upon receiving the HARQ feedback; anddetermine the mode of re-transmission as the scheduled mode if there-transmission grant is derived before expiration of the timer, and asthe grant-less mode when the timer expires without the re-transmissiongrant.
 35. The apparatus of claim 34, wherein the timer is shared by aplurality of HARQ processes on the UE.
 36. The apparatus of claim 34,wherein the timer is associated with a single HARQ process associatedwith the UL transmission.
 37. The apparatus of claim 26, wherein the DCIis configured to assign to the UE a whole system bandwidth or one of aplurality of orthogonal resources.
 38. The apparatus of claim 26,wherein the baseband circuitry is to further: determine the mode ofre-transmission as the scheduled mode if the eNB acquires a channelearlier than the UE, and as the grant-less mode if the UE acquires thechannel earlier than the eNB.
 39. The apparatus of claim 26, wherein thebaseband circuitry is to further: perform a clear channel assessment(CCA) before transmitting the UL transmission and before there-transmission.
 40. The apparatus of claim 26, wherein the basebandcircuitry is to further: encode the UL transmission data fortransmission on physical uplink shared channel (PUSCH).
 41. Theapparatus of claim 26, wherein the baseband circuitry is to further:encode the UL transmission data for transmission as a grant-less uplink(GUL) transmission.
 42. An apparatus for a user equipment (UE),comprising: baseband circuitry including one or more processors to:encode an uplink (UL) transmission to an evolved Node B (eNB) on anunlicensed spectrum; start a timer upon finishing the UL transmission;and when the timer expires without receiving a hybrid automatic repeatrequest (HARD) feedback from the eNB for the UL transmission, performone of: transmitting, as a new transmission, a packet same as the ULtransmission, and performing a re-transmission for the UL transmission.43. The apparatus of claim 42, wherein the baseband circuitry is tofurther: reset a HARQ process number associated with the ULtransmission.
 44. The apparatus of claim 43, wherein the basebandcircuitry is to further: make a predetermined number of attempts of thenew transmission or the re-transmission before resetting the HARQprocess number.
 45. An apparatus of an evolved Node B (eNB), comprising:baseband circuitry, including one or more processors, to: decode uplink(UL) transmission data received from user equipment (UE) on anunlicensed spectrum; and encode a hybrid automatic repeat request (HARQ)feedback for the UE, wherein the HARQ feedback comprises a HARQ bitmapindicating acknowledgement (ACK) and negative acknowledgement (NACK) atthe eNB for the UL transmissions associated with corresponding HARQprocess numbers.
 46. The apparatus of claim 45, wherein the basebandcircuitry is to further: encode downlink control information (DCI) fortransmission to the UE to schedule a re-transmission of one or more ofthe UL transmission indicated as NACK in the HARQ bitmap.
 47. Theapparatus of claim 45, wherein the baseband circuitry is to further:encode configuration data for the UE to configure the UE with a group ofHARQ process numbers through dedicated or broadcast radio resourcecontrol (RRC) signaling, wherein if a UL transmission indicated as NACKis associated with a HARQ process number falling within the group, are-transmission of the UL transmission can be performed without are-transmission grant from the eNB.
 48. The apparatus of claim 45,wherein the baseband circuitry is to further: encode the HARQ feedbackfor transmission to the UE during a maximum channel occupancy time(MCOT) of a second UE different from the UE.
 49. The apparatus of claim46, wherein the DCI is to be transmitted to the UE during a maximumchannel occupancy time (MCOT) of a second UE different from the UE. 50.The apparatus of claim 46, wherein the DCI is configured to assign tothe UE a whole system bandwidth or one of a plurality of orthogonalresources.